We have posted several times in the past on MS and mortality.
The SMR, is a quantity, expressed as a ratio quantifying the increase, or decrease, in mortality of a study cohort with respect to the general population. The SMR is simply the ratio of observed deaths in the study group to expected deaths in the general population. Hence a SMR of 2.7 amongst MSers means that 2.7 people died to every one person in the general population. A SMR of 2.7 is high. Of interest the SMR is higher for women with MS (2.9) than men with MS (2.5); this is because in the general population men are more likely to die young than women, hence a larger number of male deaths is the denominator. Life expectancy for pwRRMS was longer (77.8 years) than for pwPPMS (71.4 years).
Mortality decreased over the course of the study, as pwMS with onset from 1997 to 2012 showed lower rates than those who fell sick from 1953 to 1974. In comparison, pwMS younger than 20 years of age at disease onset or diagnosis showed greater mortality than those above 60 years.
Methods: All patients with incident multiple sclerosis (MS) (N=1388) with onset during 1953–2012 in Hordaland County, Western Norway, were included. Data were obtained from patient records at Haukeland University Hospital and linked to the Norwegian COD registry. Survival adjusted for sex, age and disease course were estimated by Kaplan-Meier analyses from birth and from disease onset. Mortality and COD in MS relative to the general population were examined by standardised mortality ratio (SMR).
Results: Of 1388 patients, 291 had deceased, mainly of MS (56.4%). Median life expectancy was 74.7 years for MS and 81.8 years for the general population (p<0.001); 77.2 years for women with MS and 72.2 years for men with MS (p<0.001). Life expectancy for patients with relapsing remitting MS (RRMS) was 77.8 years and 71.4 years for primary progressive MS (PPMS) (p<0.001). Overall SMR was 2.7 (p>0.0001); 2.9 in women and 2.5 in men (p=0.0009). SMR was 2.4 in RRMS and 3.9 in PPMS (p<0.0001). SMR from disease onset during 1953–1974 was 3.1; 2.6 during 1975–1996 and 0.7 during 1997–2012 (p<0.0083). No difference in cause-specific deaths were found (p=0.0871).
Conclusion: We found a 7-year shorter life expectancy and almost threefold higher mortality in MS compared with the general population. A rise in survival in MS was observed during the entire observation period.